<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
</head>
<body>
    <div id="box">
        <input type="text" v-model="mytext">
        {{ mymethod() }}
        <ul>
            <li v-for="data in datalist">
                {{ data }}
            </li>
        </ul>
    </div>

    <script>
        new Vue ({
            el: '#box',
            data: {
                mytext:'',
                datalist:['aaa','bbb','ccc','ddd', 'add','cee', 'eee']
            },
            methods:{
                mymethod(){
                    return this.datalist.filter(item=>item.includes(this.mytext))
                }
            }
        })
    </script>
</body>
</html>